The invention discloses a multipurpose over-water construction platform and a construction method and relates to the field of foundation construction of over-water bridges. The over-water construction platform comprises a steel box ring. An even number of sleeves are vertically arranged on the outer side wall of the steel box ring. The number of the sleeves is at least four. A gauge pile is vertically inserted in each sleeve. The bottoms of the gauge piles are fixed in design positions in a riverbed. The construction platform further comprises hanging systems the same as the sleeves in number. Each sleeve corresponds to one set of the hanging system. The hanging systems are used for adjusting the steel box ring and the sleeves to the design positions. The hanging systems comprise lantern rings connected with the gauge piles through hinge pins. The lantern rings are connected with the sleeves through two hanging rods respectively. The multipurpose over-water construction platform and the construction method not only can be suitable for different variations of a water level, but also can meet different elevations of the riverbed. Not only can the construction requirements be met, but also the inverted applicability is good. The range of application is wide.